The present disclosure relates to systems and methods for percutaneous implantation of a heart valve prosthesis. More particularly, the disclosure relates to systems and methods for deploying a transcatheter implantation of a stented prosthetic heart valve at a desired implantation site.
Diseased or otherwise deficient heart valves can be repaired or replaced with an implanted prosthetic heart valve. Conventionally, heart valve replacement surgery is an open-heart procedure conducted under general anesthesia, during which the heart is stopped and blood flow is controlled by a heart-lung bypass machine. Traditional open-heart surgery inflicts significant patient trauma and discomfort. Open-heart surgery also exposes the patient to a number of potential risks. These risks include infection, stroke, renal failure, and adverse effects associated with the use of the heart-lung bypass machine.
Due to the drawbacks of open-heart surgical procedures, there has been an increased interest in minimally invasive and percutaneous replacement of cardiac valves. With these percutaneous transcatheter (or transluminal) techniques, a valve prosthesis is compacted for delivery in a catheter and then advanced, for example, through an opening in the femoral artery and through the descending aorta to the heart. The valve prosthesis is then deployed in the annulus of the valve to be repaired (e.g., the aortic valve annulus). Although transcatheter techniques have attained widespread acceptance with respect to the delivery of conventional stents to restore vessel patency, only mixed results have been realized with percutaneous delivery of a relatively more complex prosthetic heart valve.
Various types and configurations of prosthetic heart valves are available for percutaneous valve procedures and continue to be refined. The actual shape and configuration of any particular prosthetic heart valve is dependent to some extent upon the native shape and size of the valve being repaired (i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve). In general, prosthetic heart valve designs attempt to replicate the functions of the valve being replaced and thus will include valve leaflet-like structures. With a bioprostheses construction, the replacement valve may include a valved vein segment that is mounted in some manner within an expandable stent frame to make a valved stent (or “stented prosthetic heart valve”). For many percutaneous delivery and implantation systems, the stent frame of the valved stent is made of a self-expanding material and construction. With these systems, the valved stent is crimped down to a desired size and held in that compressed arrangement within an outer sheath, for example. Retracting the sheath from the valved stent allows the stent to self-expand to a larger diameter, such as when the valved stent is in a desired position within a patient. In other percutaneous implantation systems, the valved stent can be initially provided in an expanded or uncrimped condition, then crimped or compressed on a balloon portion of catheter until it is as close to the diameter of the catheter as possible. Once delivered to the implantation site, the balloon in inflated to deploy the prosthesis. With either of these types of percutaneous stent delivery systems, conventional sewing of the prosthetic heart valve to the patient's native tissue is typically not necessary.
In an attempt to optimize implantation, the stented prosthetic heart valve is accurately located relative to the native annulus immediately prior to full deployment from the catheter. Successful implantation can depend on the prosthetic heart valve being intimately lodge and sealed against the native annulus. If the prosthesis is incorrectly positioned relative to the native annulus, the deployed device can leak and dislodge from the native valve implantation site. As a point of reference, this same concern does not arise in the context of other vascular stents; with these procedures. If the stent is incorrectly deployed, another stent relatively easily can be redeployed in the correct location. If a stented prosthetic heart valve is cantered or moved during retraction of the delivery device, a clinician may have to recapture the heart valve and preposition it or install a new heart valve.